Vauxhall Vectra electrical fault

Hi, looking to see if anyone has come across this problem as electrical isnt my strongest forte.

also sorry for the long spiel, just trying to be as informative as i can be

The car suffered major engine failure so i took that as a good reason to completely overhaul the car.

The engine was replaced and when i tried to start it, the engine turned over but no bang, so i checked the codes and it had an error saying swirl valves which were rightly knackered on the replacement engine, so i replaced it with the one off the original engine which was opened up and cleaned before being fitted.

after this is when i hit problems, i reconnected the battery and tried to start it and got nothing at all when i turned the key. i checked all the engine compartment, fuses etc and nothing was out of place.

the steering warning light came up on the dash aswell so i checked that and it was also fine. i should also say at this point the ecu wasn't responding to the code reader.

I left it overnight and i went out the next morning and it started turning over again but before it would start the starter motor has apparently packed up, ie all it is doing is whirring and not engaging.

so again left it for another hour, went back out and again nothing, no glow plug warming light, no engine management light and again no response to the code reader

so to summarise,

- showing steering light in warning display

- no glow plug warming light or emissions light when you turn to second point on barrell

- starter motor was only whirring and not engaging but now engine is completely unresponsive

- when i connect my code reader it is only showing link error, where as before it has always connected to the car.

my gut is the ecu is now faulty but before i call it quits i thought i would try and see if someone has had anything similiar with a fix